docs: 更新 OpenAPI 文档及提案任务清单，新增 payment_voucher_key 字段

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

docs/admin-openapi.yaml

@@ -191,6 +191,9 @@ components:
                 payment_transaction_id:
                     description: 第三方支付流水号
                     type: string
+                payment_voucher_key:
+                    description: 支付凭证对象存储Key（线下支付时存在）
+                    type: string
                 recharge_no:
                     description: 充值单号(ARCH前缀)
                     type: string
@@ -2320,6 +2323,9 @@ components:
                 payment_method:
                     description: 支付方式 (wechat:微信在线支付, offline:线下转账仅平台可用)
                     type: string
+                payment_voucher_key:
+                    description: 支付凭证对象存储Key（payment_method=offline 时必填，微信支付时忽略）
+                    type: string
                 shop_id:
                     description: 目标店铺ID，代理只能填自己店铺
                     minimum: 0